A new study suggests that men who are circumcised before their first sexual encounter may be less likely to develop prostate cancer later on.

As the study reports, sexually transmitted infections (STIs) are commonly linked to prostate cancer, since these conditions cause inflammation of the prostate — which makes it vulnerable to abnormal growth of cells. Circumcision, doctors theorize, could inhibit this cancer-causing pathway by getting rid of the foreskin that can harbor infections.

In the study, researchers from the University of Washington looked at surveys and medical records of 1,754 men with prostate cancer and 1,645 men without the disease. They found that those who were circumcised before they had sex for the first time were 15% less likely to develop prostate cancer than their uncircumcised counterparts. They were also 18% less likely to develop more-aggressive forms of the cancer.

The authors write:

The moist environment under the preputial skin may help pathogens survive for extended periods prior to direct infection. Combining the finding of a relationship between a history of STIs and [prostate cancer] risk along with a reduction in STIs in circumcised men has led to the hypothesis that circumcision might reduce [prostate cancer] development by decreasing prostatic exposure to infectious agents.

But that doesn’t mean that parents who do not circumcise their sons are putting their boys at risk for cancer. In fact, the American Academy of Pediatrics does not recommend routine circumcision, since the operation can cause complications and there isn’t strong enough evidence of the operation’s benefits to support those risks. The current results only highlight a correlation between the procedure and a lower risk of the disease, not a cause-and-effect relationship.

For now, the results are a first step toward better understanding the various factors that contribute to prostate cancer. Exposure to STIs, and the role that circumcision may play in lowering risk of those infections, might be an important component of the cancer, but it’s too early to label circumcision as a way to combat it. “That would be a huge jump,” Dr. Louis Kavoussi, chairman of urology at North Shore-LIJ Health System, told WebMD. “There are good reasons to get circumcised, but prostate-cancer prevention is not one of them.”

Which means that parents debating whether to circumcise their newborn baby boys still have a difficult decision to make about whether the operation is a good idea. The Centers for Disease Control and Prevention have not released recommendations for male circumcision but say that regardless of public-health recommendations, the decision will always be voluntary.

“At the end of the day, we feel there’s risks and benefits, and it’s up to the parents to decide what is in the best interests of their child,” Dr. Andrew Freedman, a pediatric urologist and member of the circumcision task force at the American Academy of Pediatrics, told MSNBC.

The new study was published online in the American Cancer Society journal Cancer.